Union basics in C++ - Mini Project: Build & Apply

Union basics

📖 Scenario: Imagine you want to store either an integer or a floating-point number in the same place in memory, but never both at the same time. This helps save memory when you only need one value at a time.

🎯 Goal: You will create a union in C++ that can hold either an int or a float. Then, you will assign values and print them to see how unions work.

📋 What You'll Learn

Create a union named Number with two members: int i and float f.

Create a variable num of type Number.

Assign the integer value 42 to num.i.

Assign the floating-point value 3.14f to num.f.

Print the values of num.i and num.f after each assignment.

💡 Why This Matters

🌍 Real World

Unions are useful in low-level programming where memory is limited, such as embedded systems or device drivers.

💼 Career

Understanding unions helps in systems programming, working with hardware interfaces, and optimizing memory usage.

1

Create the union Number

Write a union named Number with two members: an int called i and a float called f.

C++

// Define the union Number with int i and float f
// Your code here

Need a hint?

A union is like a struct but shares memory for all members. Use the keyword union followed by the name and curly braces.

2

Create a variable num of type Number

Declare a variable named num of type Number.

C++

union Number {
    int i;
    float f;
};

// Declare a variable num of type Number
// Your code here

Need a hint?

To create a variable of a union type, write the union name followed by the variable name and a semicolon.

3

Assign integer and float values to num

Assign the integer value 42 to num.i. Then assign the floating-point value 3.14f to num.f.

C++

union Number {
    int i;
    float f;
};

Number num;

// Assign 42 to num.i
// Assign 3.14f to num.f
// Your code here

Need a hint?

Use the dot operator to access union members and assign values like num.i = 42;.

4

Print the values of num.i and num.f

Print the values of num.i and num.f after the assignments using std::cout. Print num.i after assigning 42, then print num.f after assigning 3.14f.

C++

union Number {
    int i;
    float f;
};

Number num;

num.i = 42;
std::cout << "num.i = " << num.i << std::endl;

num.f = 3.14f;
std::cout << "num.f = " << num.f << std::endl;

// Your code here

Need a hint?

Use std::cout to print text and values. Remember to include <iostream> and use std::endl for new lines.